After-treatment of textile fabric having cured formaldehyde liberating resins and article formed thereby



United tates Pa i t F AFTER-TREATMENT OF TEXTILE FABRIC HAV- ING CURED FORMALDEHYDE LIBERATING RESINS AND ARTICLE FORMED THEREBY Philip B.. Roth, Somerviile, N. J.,. assignor' to American Cfyg lliamid Company, New York, N. Y., a corporation aine No Drawings Application June 13, 1956 Serial. No. 591,013

10 Claims. (Cl. 1-17-62) The present invention relates to the aftertr'eatmentof textile fabrics having a cured formaldehyde liberating resin or resin mixture thereon with a formaldehyde acceptor and to the fabrics so treated.

In recent years, the use of durable finishes. for "tektiles has been of considerable importance in the teittile industry. These finishes have impartedvariousproperties Jae for example, a firm resilient'hand, washer-e sistance, shrinkage control, water repellency, flame re. sistance, spot resistance and the like.

Many of these finishes are obtained by using thermosetting resins wherein formaldehyde is an essential coinponent of the resins andresin mixtures. Thus, ureaformaldehydes, melamine-formaldehydes, urea-thiourea mixed resins and their sulfona-ted derivatives amt/or their alklated derivativesare. examples of important resins in this field.

in many instances, the natureof the finislrdepends to some'extent on the amount: of the thermos etti'n'g' resin employed; A desirable'hand for lightweight woven'synthetic fabrics maybeobtained by using from /2: re 2 of a urea f'ormaldehyde resin. increasing, the amount of resin solids-to from between 5 and 15% gives a stiffer hand andimproves Wrinkle resistance-and shrinkage controi of'the cefluiosie fabrics. Modifying the ureafermatdehyde' by incorporating thiour'ea-fornraldeliyde' and partialiy ailiyfating both resins improves tbe flarne resistance and increases the .stiifn'ess ebtextiie'materials, such as. nyiotr. In the'Ia-tter instance, eonc'entratione'ofthe order of 30 to 80% resin solids based on the weigfit 'o'f the fabric are frequently employed.

Regardless.of which. resin is used, fabrics which have 2333,52 6 I Patented May 6, 1958 "ice liberated formaldehyde is reduced insufficiently to render the process of commercial importance.

Accordingly, it is an object of the present invention to provide a process for preventing the liberation of formaldehydefrom a fabric having a cured formaldehyde liberating resin thereon or reducing the amount so liberated to an acceptablecommercial level.

It is a further object to provide such a process which is adaptable to conventional mill equipment and which pensively with existing equipment.

3A particular object of the present invention relates to a process for reducing the amount of formaldehyde liberated from a -fabric having a cured formaldehyde liberating resinthereon wherein the res-iii is of the typssneh as mixed urea-thioiirea-formaldehyde type, which may be therefore may be practiced easily and relatively inexpartially alkylated or partially polymeriie'dand which may further be bisulfite modified. These resins-are normally used in rather high solids content (SO-"80% based on the weight of the fabric) in that one eftheii pii'ncipat functions is to impart a springy resilient haiidto nylon fabrics without increasing'their cor'r'ibustibility';

The resin-treated fabric having a cured formaldehyde liberating resin thereon which will yield-amounts of free ,formaldehyde in excess of 0.3% based on'theweight of '-t he':fabric when stored for 20' hours at 100- F. and at ya 100% relative humidity have been determined to be v.of the. fabricof formaldehyde when stored under the commercially undesirable. Accordingly, resiirtreated fabrics having: cured formaldehyde liberating resinsthereon which liberate 0.3% and less based on they Weight above conditions are for the most part acceptablein the trade.

- A simple test has been devised to-determine the amount of formaldehyde liberated" by a fabric treated with a formaldehyde liberating resin. In principle,- a piece of a fabric. treated with a formaldehyde liberating'oufed resin is weighed and placed in a bottle: asfor example a- 4- .ounce bottle in the presence of an excess of water, as 40,

for example cc. The fabric issuspended so a snot to be immersed in the water and the jar is tightly capped, exeluding'. all air. The bottle is stored at 100 for 20" hours, the fabric is removed, and the bottle is shaken to absorb all the formaldehyde liberated bythe fabric.

been treated therewith tend; to: liberate formaldehydeiupon storage. This is a. problem of considerable concerrrjn the industry in that fabrics so treated and having rsuch a limitation are difficult to. handle and, in addition, result in health hazards, both of which are undesirable.

Thereafter, the formaldehyde is analyzed by" fdrmi ng. a color compound with chromotropic acid soluti6ii' and'the percent of formaldehyde is estimated by the depth of the color which may be determined either spectrophotometrically or by comparing with standards of knowmconcentration. This 'erce t'is then correlated to the weight "of the fabric. The water is presentin th? Container in The eause of formaldehyde iiberation'ma'y be due, at,

least part, to the acid pH ofth'e treated fabrici 'Att-aekihg 'tiie probfem from this aspect, alkaii-neagent's have been incorporated into pad baths in order to red'uce the amount of available free formaldehyde therein and or air space in the closed bottle.

excess of the amount necessary to saturate the atmosphere This is to'as'siire a relative humidityof 100%. If a t reated fab-r'idyields formaldehydein amounts in excess $0.395," itis unacceptable for most commercial usage.

also to reduce the amount of formaldehyde which may be liberated upon storage. If formaldehyde acceptors are added in thezpad bath, the amountiof formaldehyde which is"liberafed on storage is somewhat. reduced but the rate of cure of the fabric is considerably'retarded and makes it extremely difiicult, particularly wherethe fabric is nylon, to obtain a suitable stiflhand without destroying the; saleability of the fabric. Aftentreating of cured formaldehydeliberatingresins wi'thvarious alkalineagents such as ammonium hydroxide,- sodium carbonate and other materials, has also been tried. When th'sdmzite rialsare employed in practical amounts, the amount of amount offormaldehyde liberated when a fabric so treatediisstofed for 20 hours at F. and at 100% relative humidity to 0.3% and less formaldehyde based on used either, singly, or in combination.

avoided, to

the weight of the fabric. Thereafter, the fabric is dried?" By formaldehyde acceptor, as the term is used here-. in, it is meant any compound which is capable of reacting with' formaldehyde to prevent volatilization of formaldehyde from formaldehyde liberating resins and resin mixtures which have been cured on textile fabrics. Preferably, the term is intended to include compounds which so react at roomtemperature or at temperatures either below or slightly above and which will not discolor the fabric which they are used to treat. The formaldehyde acceptors are preferably water-soluble amino and tors, either ,of these classes or of other classes which are not fully water soluble at room temperature or at'elein excess of the 0.3% based on the weight of the fabric as defined above, it is particularly applicable to those amidocornpounds, although other formaldehydefaccep- Suitable formaldehyde acceptors within the meaning of the presentinvention include urea, .dicyandiamide, eth- .ylene urea,g propylene urea, methylene urea, oxamide, propio-1, 3;diamide,, succinamide, propionamide, melaminieycertain guanaminesppolyamines such as ethylene; diamineqarid, propylene diamine; primary amines such as methyl aminej andethyl amine; alcohol amines, such as ethanol'amine and propanol amine; guanadine and guanadinesaltspmonoand poly urethanes; and SmethyI hydantoin, and. the. like. I These nitrogenous compounds capable of reacting with formaldehyde to form condensation products or their functional equivalents may be These acceptors mayqbe applied to the fabric b'yisprayresin-treated fabrics wherein the percent of liberated formaldehyde is in excess of 1% by the same test. Even more specifically, the process of the present invention is principally directed at cured resin-treated fabrics which,

when subjected to the same test, liberate amounts of formaldehyde between 1 and 3% based on the weight of the fabric. 7

I have found that when resin-treated fabrics liberate formaldehyde in the amounts of between 1 and 3% that the process of the present invention is particularly effective when the formaldehyde acceptor is applied in amounts of between 5% and 10% based on the weight of the fabric. Obviously, in some instances, slightly lower and slightly higher percentages are required or may be required to achieve the desired degree of after-treatment effectiveness. However, for the most part, treatment with formaldehyde acceptors within this range produce eminently satisfactory results.

If the amount of formaldehyde liberated is between I I a resin-treated fabric had a cured formaldehyde liberating a solution thereofor by passing the fabric to be treat-i ed througha solution and then removing the excesssby, passage through I squeeze. rolls; Other suitable means may also ,bezemployed- As noted above, the. aqueous spray =or.pad bath isolutionmay be aqueous, solvent or an aqueous-solvent mixed. solution thatucontains'sufiicient: organic solvent .toassist in solubilizing a sufiicient amount. of theacceptor to produce an effective solution.

The temperature of the spray or padding solution may be roomtemperature, i. e.' about 25 C. This ispar} ticularly desirable if thecformaldehyde acceptors require the use of an organic solvent to achieve the desired det gree of solubilityp in that volatilization and in some cases the undesirable generation of odors may be overcome. On the other hand, if the solubility of the formaldehyde acceptor isincreased byi'raising the temperature of the solution slightly, there is no "objection in employing an elevated. temperature. High temperatures near the boiling point of thesprayforpaddingsolution should be ture or if necessary atvsomewhat higher temperatures,

avoid endangering thedurable nature of the 1 being carefulnot to scorch the fabric. Preferably, the

after-treated fabric is dried tureandSOQ. e

While, generally speaking, the: process of the present invention isapplicable to any resintreated'fabrics whereat between room .temperain the'cured resin is capable of liberating, formaldehyde' amountsup appended claims.

ture.

. ing resin thereon which would liberate formaldehyde in excess of 3% based on the weight of the fabric, to about 15% of acceptor based on the weight of the fabric may be employed.

In order that the present invention may be more fully understood, the following examples are given primarily byway of illustration. No specific details therein should be construed as limitations except as they appear in the All parts and percentages are by weight unless otherwise designated.

Example 1 Eighty parts by weight of a bisulfite-modified partially methylated urea-thiourea-formaldehyde resin product, 0.52 part of ammonium chloride, and 19.40 parts of water suificient to yield a total of parts are made up into a padding solution containing 64% solids. Through this padding solution, nylon Rochelle netting was passed and ,the excess of the pad bath solution was removed by perature.

Example 2 Example 1 was repeated except that in the afore-treatment the fabric was treated with 10% of urea based on its 7 Thereafter, the fabric was dried at room temperaweight.

Example 3 The procedure of Example 1 was followed except that there was no after-treatment with urea. This example was used as the control in the data recorded in the chart set forth hereinbelow.

, After so hours j storage at 100 Treatment F. and 100% Odor Band Color Fire RBI-percent m Retardformoldehydo ant-y liberated Example-N0. 3 (Control) 1.8 51. ECHO Std--- Std OK. Example No. 1 sprayed with 5%:nroa 0:8 V. at. HOHO-. Std--- S 0K. EmrnplaNoA sprayed with 10% urea N n Std-- 0K.

1 (his band 10% urea based on weight of cloth.

It will thus be. obs rved that the omission of the use of a formaldehyde acceptor as an after-treatment resulted in 6 times.as-m'uchv formaldehyde being liberated aswhen the after-treatment with of urea based on the weight of the fabric was employed. In addition, it will be noted that h n a are; wasemplgysd. no d of for a hyde developed whatsoever under the above test conditions nor was there any detrimental effect on the hand, color or fire retardancy of the nylon fabric.

Example 4 Nylon Rochelle netting was treated as in Example 1 except that a 5% solution of succinamide in acetone was used in place of the aqueous urea solution. After this treatment the fabric liberated less than 0.3% formaldehyde.

The process of the present invention is particularly adaptable to resin-treated fabrics having cured formaldehyde liberating resins which liberate formaldehyde in amounts on the order of from 1 to 3% when subject to test conditions set forth above. Resins which liberate formaldehyde in these amounts under the test conditions are, for the most part, resins which are applied in rather large quantities, as for example, of the order of 30 to 80% or more based on the weight of the textile fabric. In particular, the resins adapted to impart flame resistance to nylon fabrics may be considered to be within this class. Here, the resins are added on in rather large amounts in order to impart the desired degree of resiliency and stiffness to the particular fabrics.

A resin. composition of this type, when applied to nylon netting to give about a 60 to 80% solids add-on, imparts a springy hand to the fabric and also retains the burning characteristics of the untreated nylon. However, on storage, formaldehyde is liberated and the obnoxious odor which results is undesirable.

As another example of a resin which liberates formaldehyde and which is added to nylon fabric to impart a springy hand and which is added on in relatively large quantities are partially alkylated thiourea-formaldehyde resinous compositions. These resinous compositions which contain on the order of about 50% thiourea can be blended with partially polymerized urea-formaldehydes, methylated methylol melamines or dimethylol thiourea to yield mixtures containing on the order of about 18% thiourea. An important disadvantage of them is the [fact that they liberate formaldehyde when stored.

An additional example of such resins and the resin employed in the treatment of nylon in Examples 1 to 4 are the partially alkylated, partially polymerized ureathiourea resin which is bisulfite modified.

These resins, as well as any resin which would liberate formaldehyde in amounts in excess of 0.3% based on the weight of the fabric in accordance with the test abovedefined may be applied to the fabric by any one of a large number of conventional processes well-known in the art. For example, a pad bath may be prepared containing the correct amount of solids to produce the desired finish and a catalyst such as an ammonium halide, an alkali metal salt, amine hydrochlorides or organic acids such as oxalic or tartaric may be added to the bath. Water may be then added to give the correct concentration of solids and the fabric padded therethrough, the excess of the pad bath solution being removed by squeezing, centrifuging, or other means. Thereafter, the fabric is dried and the resin cured, as for example, for 5 minutes at 250 F. to 5 seconds at 450 F. and preferably for from 1 to 3 minutes at from 360 F. to 290 F., depending upon the nature of the fabric and the cure desired.

1 claim:

1. A process for reducing the amount of formaldehyde liberated from a fabric having a cured formaldehyde liberating resin thereon, said cured resin being capable of liberating formaldehyde in amounts in excess of 0.3% based on the weight of the fabric when stored for amount of a formaldehyde acceptor, said formaldehyde acceptor being a nitrogenous compound capable of reacting with formaldehyde to form a condensation prodnot, said amount being, sufficient toreduce, the amount of formaldehyde liberated when fabric so treated is stored for 20 hours at 100 F. and 100% relative humidity to 0.3% and less based on the weight'of the fabric, and thereafter drying the fabric.

2. A process for reducing the amount of formaldehyde liberated from a fabric having a cured formaldehyde liberating resin thereon, said cured resin being capable of liberating formaldehyde in amounts in excess of 0.3% based on the weight of the fabric when stored for 20 hours at 100 F. and at 100% relative humidity, which comprises after-treating said resin fabric with an amount of an amide, formaldehyde acceptor, said amide acceptor being applied in an amount sutncient to reduce the amount of formaldehyde liberated when fabric so treated is stored for 20 hours at 100 F. and 100% relative humidity to 0.3% and less based on the weight of the fabric, and thereafter drying the fabric.

3. A process for reducing the amount of formaldehyde liberated from a fabric having a cured formaldehyde liberating resin thereon, said resin being capable of lib erating formaldehyde in amounts in excess of 0.3% based on the weight of the fabric, when stored for 20 hours at 100 F. and at 100% relative humidity which comprises after-treating said resin-treated fabric with between 2% and 15% of a formaldehyde acceptor, said formaldehyde acceptor being a nitrogenous compound capable of reacting with formaldehyde to form a condensation product, said amount of formaldehyde acceptor being based on the weight of the fabric, and thereafter drying the fabric.

4. A process for reducing the amount of formaldehyde liberated from a fabric having a cured formaldehyde liberating resin thereon, said resin being capable of liberating formaldehyde in amounts of between 1 and 3% based on the weight of the fabric, when stored for 20 hours at 100 F. and at 100% relative humidity which comprises after-treating said resin-treated fabric with between about 5% and about 10% of a water-soluble amide formaldehyde acceptor based on the weight of the fabric, said amide being applied as a solution, and thereafter drying the fabric.

5. A process for reducing the amount of formaldehyde liberated from a fabric having a cured formaldehyde liberating resin thereon, said resin being capable of liberating formaldehyde in amounts of between 1 and 3% based on the weight of the fabric, when stored for 20 hours at 100 F. and at 100% relative humidity, which comprises after-treating said resin-treated fabric with between about 5% and about 10% of urea based on the weight of the fabric, said urea being applied as an aqueous solution,

' hours at F. and 100% relative humidity which comprises after-treating said resin-treated fabric with between about 5 and about 10% of urea based on the weight of the fabric, said urea being applied by spraying an aqueous solution thereof, and thereafter drying the fabric.

7. A process for reducing the amount of formaldehyde liberated from a nylon fabric having a cured formaldehyde liberating resin thereon, said resin being capable of liberating formaldehyde in amounts of between 1% and 3% based on the weight of the fabric, when stored for 20 hours at 100 F. and 100% relative humidity, which comprises spraying said resin-treated nylon fabric with from between about 5 and about 10% of urea, based on 7 the weight of the fabric, eaid urea being sprayed as an References Cited in the file of this patent aqueous solution, and ther'eafterdrying the fabric. UNITED STATES PATENTS I 8. A t b di th f f j m 99 ng v e pmms 2,267,276 Hager Dec. 23, 1941 9." Atextile fabric treated according to the process of 5 FOREIGN PATENTS claim6; 1 V Y I 10; A nylon textile fabric treated according to the proe- 312,443 Great Britain May 30, 1929 UNITED STATES PA'EENT OFFICE CERTIFICATE OF CORRECTION Patent N06 2,833,670 I May 6, 1958 Philip B, B05511 V I1; is hereby certified that efri' appear in the printed specificaEi-on f the above numberd patent requiring correction and that the said Letters Patent should read as corrc'bed below.

Column 1, line 30, f'c'a'r "alklated" read ==alkylated==g column 4, line 44,1501:- "Rochelle netting" Iad fiachelle neuting lines 54 and 55, for "afore treatmnc" rad ===after treatment==g column 5, line 12,

for "Rochelle netting" read ===Rachelle netti11g-=-=a Signed and sealed this 8th day of July 1958 (SEAL) Attest:

KARL H, AXLINE 7 ROBERT c. WATSON Attesting Officer Commissioner of Patents 

1. A PROCESS FOR REDUCING THE AMOUNT OF FORMALDEHYDE LIBERATED FROM A FABRIC HAVING A CURED FORMALDEHYDE LIBERATING RESIN THEREON, SAID CURED RESIN BEING CAPABLE OF LIBERATING FORMALDEHYDE IN AMOUNTS IN EXCESS OF 0.3% BASED ON THE WEIGHT OF THE FABRIC WHEN STORED FOR 20 HOURS AT 100*F. AND AT 100% RELATIVE HUMIDITY, WHICH COMPRISES AFTER-TREATING SAID RESIN-TREATED FABRIC WITH AN AMOUNT OF A FORMALDEHYDE ACCEPTOR, SAID FORMALDEHYDE ACCEPTOR BEING A NITROGENOUS COMPOUND CAPABLE OF REACTING WITH FORMALDEHYDE TO FORM A CONDENSATION PRODUCT, SAID AMOUNT BEING SUFFICIENT TO REDUCE THE AMOUNT OF FORMALDEHYDE LIBERATED WHEN FABRIC SO TREATED IS STORED FOR 20 HOURS AT 100*F. AND 100% RELATIVE HUMIDITY TO 0.3% AND LESS BASED ON THE WEIGHT OF THE FABRIC, AND THEREAFTER DRYING THE FABRIC. 